Gel permeation chromatography with crosslinked polystyrene gels and poor and theta solvents for polystyrene, 3. Temperature dependence of universal calibration for trans‐decalin

Abstract

AbstractGel permeation chromatography calibrations for polystyrene (PS) standards and poly(dimethylsiloxane) (PDS) fractions have been obtained with crosslinked polystyrene gels using trans‐decalin as eluent at 25, 60, 100, and 138°C. At these temperatures, the Mark‐Houwink exponent for PS in trans‐decalin is 0,52, 0,64, 0,67, and 0,67, respectively. The eluent is a good solvent for PDS at all four temperatures. At 25 and 60°C, the plot of log hydrodynamic volume versus retention volume for PS is displaced to high retention volumes with respect to the plot for PDS, the displacement increasing as the retention volume increases. The deviation between the two plots decreases as the temperature is raised, becoming almost negligible at 100°C. trans‐Decalin gives rise to broadened gel permeation chromatograms, because of the high viscosity of the cluent. However, additional broadening occurs for PS at 25 and 60°C, the broadening increasing as retention volume increases, and as temperature falls. Both the additional retention and broadening for PS are explained by solute‐gel interactions. The calibration results are plotted according to equations representing network‐limited partition and network‐limited adsorption mechanisms. The distribution coefficient for solute‐gel interaction effects. Kp, falls as the temperature is raised. When Kp is greater than unity, it is shown that the hydrodynamic volume universal calibration method is applicable, if the retention parameter is changed from VR to (VR–V0)/Kp, where V0 is the interstitial volume.